SAFE public projects git trees. - safe/jmp/linux-2.6/blob - security/keys/request_key.c

   1 /* Request a key from userspace
   2  *
   3  * Copyright (C) 2004-2007 Red Hat, Inc. All Rights Reserved.
   4  * Written by David Howells (dhowells@redhat.com)
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the License, or (at your option) any later version.
  10  *
  11  * See Documentation/keys-request-key.txt
  12  */
  13
  14 #include <linux/module.h>
  15 #include <linux/sched.h>
  16 #include <linux/kmod.h>
  17 #include <linux/err.h>
  18 #include <linux/keyctl.h>
  19 #include <linux/slab.h>
  20 #include "internal.h"
  21
  22 #define key_negative_timeout    60      /* default timeout on a negative key's existence */
  23
  24 /*
  25  * wait_on_bit() sleep function for uninterruptible waiting
  26  */
  27 static int key_wait_bit(void *flags)
  28 {
  29         schedule();
  30         return 0;
  31 }
  32
  33 /*
  34  * wait_on_bit() sleep function for interruptible waiting
  35  */
  36 static int key_wait_bit_intr(void *flags)
  37 {
  38         schedule();
  39         return signal_pending(current) ? -ERESTARTSYS : 0;
  40 }
  41
  42 /*
  43  * call to complete the construction of a key
  44  */
  45 void complete_request_key(struct key_construction *cons, int error)
  46 {
  47         kenter("{%d,%d},%d", cons->key->serial, cons->authkey->serial, error);
  48
  49         if (error < 0)
  50                 key_negate_and_link(cons->key, key_negative_timeout, NULL,
  51                                     cons->authkey);
  52         else
  53                 key_revoke(cons->authkey);
  54
  55         key_put(cons->key);
  56         key_put(cons->authkey);
  57         kfree(cons);
  58 }
  59 EXPORT_SYMBOL(complete_request_key);
  60
  61 /*
  62  * request userspace finish the construction of a key
  63  * - execute "/sbin/request-key <op> <key> <uid> <gid> <keyring> <keyring> <keyring>"
  64  */
  65 static int call_sbin_request_key(struct key_construction *cons,
  66                                  const char *op,
  67                                  void *aux)
  68 {
  69         const struct cred *cred = current_cred();
  70         key_serial_t prkey, sskey;
  71         struct key *key = cons->key, *authkey = cons->authkey, *keyring;
  72         char *argv[9], *envp[3], uid_str[12], gid_str[12];
  73         char key_str[12], keyring_str[3][12];
  74         char desc[20];
  75         int ret, i;
  76
  77         kenter("{%d},{%d},%s", key->serial, authkey->serial, op);
  78
  79         ret = install_user_keyrings();
  80         if (ret < 0)
  81                 goto error_alloc;
  82
  83         /* allocate a new session keyring */
  84         sprintf(desc, "_req.%u", key->serial);
  85
  86         keyring = keyring_alloc(desc, current_fsuid(), current_fsgid(), current,
  87                                 KEY_ALLOC_QUOTA_OVERRUN, NULL);
  88         if (IS_ERR(keyring)) {
  89                 ret = PTR_ERR(keyring);
  90                 goto error_alloc;
  91         }
  92
  93         /* attach the auth key to the session keyring */
  94         ret = __key_link(keyring, authkey);
  95         if (ret < 0)
  96                 goto error_link;
  97
  98         /* record the UID and GID */
  99         sprintf(uid_str, "%d", cred->fsuid);
 100         sprintf(gid_str, "%d", cred->fsgid);
 101
 102         /* we say which key is under construction */
 103         sprintf(key_str, "%d", key->serial);
 104
 105         /* we specify the process's default keyrings */
 106         sprintf(keyring_str[0], "%d",
 107                 cred->thread_keyring ?
 108                 cred->thread_keyring->serial : 0);
 109
 110         prkey = 0;
 111         if (cred->tgcred->process_keyring)
 112                 prkey = cred->tgcred->process_keyring->serial;
 113
 114         if (cred->tgcred->session_keyring)
 115                 sskey = rcu_dereference(cred->tgcred->session_keyring)->serial;
 116         else
 117                 sskey = cred->user->session_keyring->serial;
 118
 119         sprintf(keyring_str[2], "%d", sskey);
 120
 121         /* set up a minimal environment */
 122         i = 0;
 123         envp[i++] = "HOME=/";
 124         envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
 125         envp[i] = NULL;
 126
 127         /* set up the argument list */
 128         i = 0;
 129         argv[i++] = "/sbin/request-key";
 130         argv[i++] = (char *) op;
 131         argv[i++] = key_str;
 132         argv[i++] = uid_str;
 133         argv[i++] = gid_str;
 134         argv[i++] = keyring_str[0];
 135         argv[i++] = keyring_str[1];
 136         argv[i++] = keyring_str[2];
 137         argv[i] = NULL;
 138
 139         /* do it */
 140         ret = call_usermodehelper_keys(argv[0], argv, envp, keyring,
 141                                        UMH_WAIT_PROC);
 142         kdebug("usermode -> 0x%x", ret);
 143         if (ret >= 0) {
 144                 /* ret is the exit/wait code */
 145                 if (test_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags) ||
 146                     key_validate(key) < 0)
 147                         ret = -ENOKEY;
 148                 else
 149                         /* ignore any errors from userspace if the key was
 150                          * instantiated */
 151                         ret = 0;
 152         }
 153
 154 error_link:
 155         key_put(keyring);
 156
 157 error_alloc:
 158         kleave(" = %d", ret);
 159         complete_request_key(cons, ret);
 160         return ret;
 161 }
 162
 163 /*
 164  * call out to userspace for key construction
 165  * - we ignore program failure and go on key status instead
 166  */
 167 static int construct_key(struct key *key, const void *callout_info,
 168                          size_t callout_len, void *aux,
 169                          struct key *dest_keyring)
 170 {
 171         struct key_construction *cons;
 172         request_key_actor_t actor;
 173         struct key *authkey;
 174         int ret;
 175
 176         kenter("%d,%p,%zu,%p", key->serial, callout_info, callout_len, aux);
 177
 178         cons = kmalloc(sizeof(*cons), GFP_KERNEL);
 179         if (!cons)
 180                 return -ENOMEM;
 181
 182         /* allocate an authorisation key */
 183         authkey = request_key_auth_new(key, callout_info, callout_len,
 184                                        dest_keyring);
 185         if (IS_ERR(authkey)) {
 186                 kfree(cons);
 187                 ret = PTR_ERR(authkey);
 188                 authkey = NULL;
 189         } else {
 190                 cons->authkey = key_get(authkey);
 191                 cons->key = key_get(key);
 192
 193                 /* make the call */
 194                 actor = call_sbin_request_key;
 195                 if (key->type->request_key)
 196                         actor = key->type->request_key;
 197
 198                 ret = actor(cons, "create", aux);
 199
 200                 /* check that the actor called complete_request_key() prior to
 201                  * returning an error */
 202                 WARN_ON(ret < 0 &&
 203                         !test_bit(KEY_FLAG_REVOKED, &authkey->flags));
 204                 key_put(authkey);
 205         }
 206
 207         kleave(" = %d", ret);
 208         return ret;
 209 }
 210
 211 /*
 212  * get the appropriate destination keyring for the request
 213  * - we return whatever keyring we select with an extra reference upon it which
 214  *   the caller must release
 215  */
 216 static void construct_get_dest_keyring(struct key **_dest_keyring)
 217 {
 218         struct request_key_auth *rka;
 219         const struct cred *cred = current_cred();
 220         struct key *dest_keyring = *_dest_keyring, *authkey;
 221
 222         kenter("%p", dest_keyring);
 223
 224         /* find the appropriate keyring */
 225         if (dest_keyring) {
 226                 /* the caller supplied one */
 227                 key_get(dest_keyring);
 228         } else {
 229                 /* use a default keyring; falling through the cases until we
 230                  * find one that we actually have */
 231                 switch (cred->jit_keyring) {
 232                 case KEY_REQKEY_DEFL_DEFAULT:
 233                 case KEY_REQKEY_DEFL_REQUESTOR_KEYRING:
 234                         if (cred->request_key_auth) {
 235                                 authkey = cred->request_key_auth;
 236                                 down_read(&authkey->sem);
 237                                 rka = authkey->payload.data;
 238                                 if (!test_bit(KEY_FLAG_REVOKED,
 239                                               &authkey->flags))
 240                                         dest_keyring =
 241                                                 key_get(rka->dest_keyring);
 242                                 up_read(&authkey->sem);
 243                                 if (dest_keyring)
 244                                         break;
 245                         }
 246
 247                 case KEY_REQKEY_DEFL_THREAD_KEYRING:
 248                         dest_keyring = key_get(cred->thread_keyring);
 249                         if (dest_keyring)
 250                                 break;
 251
 252                 case KEY_REQKEY_DEFL_PROCESS_KEYRING:
 253                         dest_keyring = key_get(cred->tgcred->process_keyring);
 254                         if (dest_keyring)
 255                                 break;
 256
 257                 case KEY_REQKEY_DEFL_SESSION_KEYRING:
 258                         rcu_read_lock();
 259                         dest_keyring = key_get(
 260                                 rcu_dereference(cred->tgcred->session_keyring));
 261                         rcu_read_unlock();
 262
 263                         if (dest_keyring)
 264                                 break;
 265
 266                 case KEY_REQKEY_DEFL_USER_SESSION_KEYRING:
 267                         dest_keyring =
 268                                 key_get(cred->user->session_keyring);
 269                         break;
 270
 271                 case KEY_REQKEY_DEFL_USER_KEYRING:
 272                         dest_keyring = key_get(cred->user->uid_keyring);
 273                         break;
 274
 275                 case KEY_REQKEY_DEFL_GROUP_KEYRING:
 276                 default:
 277                         BUG();
 278                 }
 279         }
 280
 281         *_dest_keyring = dest_keyring;
 282         kleave(" [dk %d]", key_serial(dest_keyring));
 283         return;
 284 }
 285
 286 /*
 287  * allocate a new key in under-construction state and attempt to link it in to
 288  * the requested place
 289  * - may return a key that's already under construction instead
 290  */
 291 static int construct_alloc_key(struct key_type *type,
 292                                const char *description,
 293                                struct key *dest_keyring,
 294                                unsigned long flags,
 295                                struct key_user *user,
 296                                struct key **_key)
 297 {
 298         struct key *key;
 299         key_ref_t key_ref;
 300
 301         kenter("%s,%s,,,", type->name, description);
 302
 303         mutex_lock(&user->cons_lock);
 304
 305         key = key_alloc(type, description,
 306                         current_fsuid(), current_fsgid(), current, KEY_POS_ALL,
 307                         flags);
 308         if (IS_ERR(key))
 309                 goto alloc_failed;
 310
 311         set_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags);
 312
 313         down_write(&dest_keyring->sem);
 314
 315         /* attach the key to the destination keyring under lock, but we do need
 316          * to do another check just in case someone beat us to it whilst we
 317          * waited for locks */
 318         mutex_lock(&key_construction_mutex);
 319
 320         key_ref = search_process_keyrings(type, description, type->match,
 321                                           current);
 322         if (!IS_ERR(key_ref))
 323                 goto key_already_present;
 324
 325         __key_link(dest_keyring, key);
 326
 327         mutex_unlock(&key_construction_mutex);
 328         up_write(&dest_keyring->sem);
 329         mutex_unlock(&user->cons_lock);
 330         *_key = key;
 331         kleave(" = 0 [%d]", key_serial(key));
 332         return 0;
 333
 334 key_already_present:
 335         mutex_unlock(&key_construction_mutex);
 336         if (dest_keyring)
 337                 up_write(&dest_keyring->sem);
 338         mutex_unlock(&user->cons_lock);
 339         key_put(key);
 340         *_key = key = key_ref_to_ptr(key_ref);
 341         kleave(" = -EINPROGRESS [%d]", key_serial(key));
 342         return -EINPROGRESS;
 343
 344 alloc_failed:
 345         mutex_unlock(&user->cons_lock);
 346         *_key = NULL;
 347         kleave(" = %ld", PTR_ERR(key));
 348         return PTR_ERR(key);
 349 }
 350
 351 /*
 352  * commence key construction
 353  */
 354 static struct key *construct_key_and_link(struct key_type *type,
 355                                           const char *description,
 356                                           const char *callout_info,
 357                                           size_t callout_len,
 358                                           void *aux,
 359                                           struct key *dest_keyring,
 360                                           unsigned long flags)
 361 {
 362         struct key_user *user;
 363         struct key *key;
 364         int ret;
 365
 366         user = key_user_lookup(current_fsuid());
 367         if (!user)
 368                 return ERR_PTR(-ENOMEM);
 369
 370         construct_get_dest_keyring(&dest_keyring);
 371
 372         ret = construct_alloc_key(type, description, dest_keyring, flags, user,
 373                                   &key);
 374         key_user_put(user);
 375
 376         if (ret == 0) {
 377                 ret = construct_key(key, callout_info, callout_len, aux,
 378                                     dest_keyring);
 379                 if (ret < 0)
 380                         goto construction_failed;
 381         }
 382
 383         key_put(dest_keyring);
 384         return key;
 385
 386 construction_failed:
 387         key_negate_and_link(key, key_negative_timeout, NULL, NULL);
 388         key_put(key);
 389         key_put(dest_keyring);
 390         return ERR_PTR(ret);
 391 }
 392
 393 /*
 394  * request a key
 395  * - search the process's keyrings
 396  * - check the list of keys being created or updated
 397  * - call out to userspace for a key if supplementary info was provided
 398  * - cache the key in an appropriate keyring
 399  */
 400 struct key *request_key_and_link(struct key_type *type,
 401                                  const char *description,
 402                                  const void *callout_info,
 403                                  size_t callout_len,
 404                                  void *aux,
 405                                  struct key *dest_keyring,
 406                                  unsigned long flags)
 407 {
 408         struct key *key;
 409         key_ref_t key_ref;
 410
 411         kenter("%s,%s,%p,%zu,%p,%p,%lx",
 412                type->name, description, callout_info, callout_len, aux,
 413                dest_keyring, flags);
 414
 415         /* search all the process keyrings for a key */
 416         key_ref = search_process_keyrings(type, description, type->match,
 417                                           current);
 418
 419         if (!IS_ERR(key_ref)) {
 420                 key = key_ref_to_ptr(key_ref);
 421         } else if (PTR_ERR(key_ref) != -EAGAIN) {
 422                 key = ERR_CAST(key_ref);
 423         } else  {
 424                 /* the search failed, but the keyrings were searchable, so we
 425                  * should consult userspace if we can */
 426                 key = ERR_PTR(-ENOKEY);
 427                 if (!callout_info)
 428                         goto error;
 429
 430                 key = construct_key_and_link(type, description, callout_info,
 431                                              callout_len, aux, dest_keyring,
 432                                              flags);
 433         }
 434
 435 error:
 436         kleave(" = %p", key);
 437         return key;
 438 }
 439
 440 /*
 441  * wait for construction of a key to complete
 442  */
 443 int wait_for_key_construction(struct key *key, bool intr)
 444 {
 445         int ret;
 446
 447         ret = wait_on_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT,
 448                           intr ? key_wait_bit_intr : key_wait_bit,
 449                           intr ? TASK_INTERRUPTIBLE : TASK_UNINTERRUPTIBLE);
 450         if (ret < 0)
 451                 return ret;
 452         return key_validate(key);
 453 }
 454 EXPORT_SYMBOL(wait_for_key_construction);
 455
 456 /*
 457  * request a key
 458  * - search the process's keyrings
 459  * - check the list of keys being created or updated
 460  * - call out to userspace for a key if supplementary info was provided
 461  * - waits uninterruptible for creation to complete
 462  */
 463 struct key *request_key(struct key_type *type,
 464                         const char *description,
 465                         const char *callout_info)
 466 {
 467         struct key *key;
 468         size_t callout_len = 0;
 469         int ret;
 470
 471         if (callout_info)
 472                 callout_len = strlen(callout_info);
 473         key = request_key_and_link(type, description, callout_info, callout_len,
 474                                    NULL, NULL, KEY_ALLOC_IN_QUOTA);
 475         if (!IS_ERR(key)) {
 476                 ret = wait_for_key_construction(key, false);
 477                 if (ret < 0) {
 478                         key_put(key);
 479                         return ERR_PTR(ret);
 480                 }
 481         }
 482         return key;
 483 }
 484 EXPORT_SYMBOL(request_key);
 485
 486 /*
 487  * request a key with auxiliary data for the upcaller
 488  * - search the process's keyrings
 489  * - check the list of keys being created or updated
 490  * - call out to userspace for a key if supplementary info was provided
 491  * - waits uninterruptible for creation to complete
 492  */
 493 struct key *request_key_with_auxdata(struct key_type *type,
 494                                      const char *description,
 495                                      const void *callout_info,
 496                                      size_t callout_len,
 497                                      void *aux)
 498 {
 499         struct key *key;
 500         int ret;
 501
 502         key = request_key_and_link(type, description, callout_info, callout_len,
 503                                    aux, NULL, KEY_ALLOC_IN_QUOTA);
 504         if (!IS_ERR(key)) {
 505                 ret = wait_for_key_construction(key, false);
 506                 if (ret < 0) {
 507                         key_put(key);
 508                         return ERR_PTR(ret);
 509                 }
 510         }
 511         return key;
 512 }
 513 EXPORT_SYMBOL(request_key_with_auxdata);
 514
 515 /*
 516  * request a key (allow async construction)
 517  * - search the process's keyrings
 518  * - check the list of keys being created or updated
 519  * - call out to userspace for a key if supplementary info was provided
 520  */
 521 struct key *request_key_async(struct key_type *type,
 522                               const char *description,
 523                               const void *callout_info,
 524                               size_t callout_len)
 525 {
 526         return request_key_and_link(type, description, callout_info,
 527                                     callout_len, NULL, NULL,
 528                                     KEY_ALLOC_IN_QUOTA);
 529 }
 530 EXPORT_SYMBOL(request_key_async);
 531
 532 /*
 533  * request a key with auxiliary data for the upcaller (allow async construction)
 534  * - search the process's keyrings
 535  * - check the list of keys being created or updated
 536  * - call out to userspace for a key if supplementary info was provided
 537  */
 538 struct key *request_key_async_with_auxdata(struct key_type *type,
 539                                            const char *description,
 540                                            const void *callout_info,
 541                                            size_t callout_len,
 542                                            void *aux)
 543 {
 544         return request_key_and_link(type, description, callout_info,
 545                                     callout_len, aux, NULL, KEY_ALLOC_IN_QUOTA);
 546 }
 547 EXPORT_SYMBOL(request_key_async_with_auxdata);